Question: A jar contains $10$ red jelly beans, $9$ green jelly beans, and $8$ blue jelly beans. If a jelly bean is randomly chosen, what is the probability that it is not green?
Explanation: There are $10 + 9 + 8 = 27$ jelly beans in the jar. There are $9$ green jelly beans. That means $27 - 9 = 18$ are not green. The probability is $ \frac{18}{27} = \dfrac{2}{3}$.